1. Field of the Invention
The present invention relates to a gene cluster involved in biosynthesis of isopentenyl diphosphate in the non-mevalonate pathway of Hevea brasiliensis. 
2. Background Art
All kinds of steroids, terpenoids, carotinoids, and all kinds of vitamins are composed of plural 5-carbon isoprenes covalently bound to one another. The basic isoprene structure is called “isoprene unit”, and a compound having isoprene unit is generically called “isoprenoid”. Isopentenyl diphosphate (IPP), a compound having five-carbons, serves as a unit in condensation reaction when an isoprenoid compound is synthesized. The two pathways of mevalonate pathway and the non-mevalonate pathway are known as the IPP biosynthesis pathways. In plants, it is said that the mevalonate pathway functions in cell cytoplasm and the non-mevalonate pathway functions in plastids. In Escherichia coli, each of the non-mevalonate pathway genes is isolated, and its functions are confirmed. In Hevea brasiliensis, on the other hand, the sequences of the gene cluster have not been reported. FIG. 1 shows the non-mevalonate pathway of IPP synthesis. Details about isoprenoid biosynthesis by the non-mevalonate pathway are given in the general remarks in W. Eisenreich et al., Cell Mol. Life Sci. 61 (2004) 1401-1426, for example.
In the non-mevalonate pathway, firstly glyceraldehyde 3-phosphate and pyruvic acid are catalyzed by 1-deoxy-D-xylulose 5-phosphate synthase (DXS) to undergo condensation accompanied by decarboxylation reaction, thereby 1-deoxy-D-xylulose 5-phosphate (DXP) is formed. DXS catalyzes transfer of 2 carbonates using thiamine diphosphate as a cofactor by the reaction mechanism similar to transketolase and pyruvic acid decarboxylase.
DXP undergoes transferring reaction and then reduced through catalysis by 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), thereby forms 2-C-methyl-D-erythritol-4-phosphate (MEP). MEP is conjugated with CDP by MEP cytidyltransferase (MCT) to form 4-(cytidine-5′-diphospho)-2-C-methyl-D-erythritol (MEPPC). The 3-Hydroxyl group of MEPPC is phosphorylated by 4-(cytidine-5′-diphospho)-2-C-methyl-D-erythritol kinase (CMK), and MEPPC is converted to 4-(cytidine-5′-diphospho)-2-C-methyl-D-erythritol 2-phosphate (MEPPCP).
MEPPCP is catalyzed by 2-C-methylerythritol 2,4-cyclodiphosphate synthase (MECPS) to form 2-C-methylerythritol 2,4-cyclodiphosphate (MECPP). Next, MSCPP is reductively converted to 1-hydroxy-2-methyl-2-(E)-butenyl 4-phosphate (HMBPP). Further, IPP and DMAPP are biosynthesized from HMBPP.